Love online: one-third of US married couples now meet on the web

If we forgot our entire relationship, we’d have that fizzy feeling of excitement when they called again (Getty Images)

With a vote expected later today the House of Lords appears split on gay marriage - but a new study from America suggests that the real shift in modern matrimony doesn't concern the sexuality of couples so much as how they meet.

Researchers found that between 2005 and 2012 more than one third of US marriages began with online dating.

The study, based on a representative group of 19,131 people, also revealed that couples who meet online are slightly happier and more likely to stay together.

Respondents who e-romanced were older but, by the end of the survey period, just 5.96 per cent had divorced - compared to 7.67 per cent of couples who met offline.

"These data suggest that the internet may be altering the dynamics and outcomes of marriage itself", said John Cacioppo, lead author of the study, which will be published in the Proceedings of the National Academy of Sciences.